Durable small gauge wire electrical conductor suitable for delivery of high intensity energy pulses

Abstract

Implantable medical devices intended for electrostimulation and sensing devices typically incorporate one or more electrical conductors as leads for electrical stimulation to, or retrieval of localized sensing data from, discrete points in the body, such as the heart. Certain applications require delivery of high intensity electrical pulses, i.e. CRTs, or defibrillators. As described herein a CRT delivers high energy pulses via a durable fine wire lead formed of a glass, silica, sapphire or crystalline quartz fiber core with a metal coating. A unipolar electrical conductor can have an outer diameter of about 150 microns or even smaller. The buffered fibers support conduction of high intensity electrical pulses as required for internal or external defibrillators, or other biomedical applications, as well as non-medical applications. Defibrillation pulses can be transmitted through less cross-sectional area of metal in the subject fine wire conductor than would be the case with conventional solid core metal wires. Multiple such coated fibers can act as a single conductor. An outer protective sheath of a flexible polymer material can be included.

1 . In combination, a high intensity energy electrical pulsing device and a durable fine wire conductor connected to the device, such that the conductor is subjected to high energy, short duration pulses, comprising:
 a high energy electrical pulsing device, and   a flexible, durable fine wire conductor electrically connected to the electrical pulsing device so as to carry a high energy electrical pulse, the fine wire conductor comprising a drawn glass/silica fiber core, and a conductive metal buffer cladding on the core.   
     
     
         2 . The combination defined in  claim 1 , wherein the outer diameter of the fine wire lead at the metal cladding is no greater than about 750 microns. 
     
     
         3 . The combination defined in  claim 1 , wherein the fine wire conductor is sufficiently flexible to bend to a radius of about 8 to 10 times the fiber core diameter without damage. 
     
     
         4 . The combination defined in  claim 1 , wherein the glass/silica fiber core has a diameter no greater than about 450 microns. 
     
     
         5 . The combination defined in  claim 1 , with an outer diameter no greater than about 300 microns. 
     
     
         6 . The combination defined in  claim 1 , wherein the drawn glass/silica fiber core is hollow. 
     
     
         7 . The combination defined in  claim 1 , wherein a conductor wire is positioned in the center of the fiber core, so that the fine wire conductor is bipolar. 
     
     
         8 . The combination defined in  claim 1 , wherein the glass/silica fiber core comprises silica. 
     
     
         9 . The combination defined in  claim 1 , wherein the metal buffer cladding is hermetically sealed to the glass/silica fiber core. 
     
     
         10 . The combination defined in  claim 1 , wherein the glass/silica fiber core comprises a proofed fiber. 
     
     
         11 . The combination defined in  claim 10 , wherein the fiber is proofed to at least about 75% of the intrinsic strength value of the glass/silica material. 
     
     
         12 . The combination defined in  claim 1 , wherein the metallic buffer cladding is aluminum. 
     
     
         13 . The combination defined in  claim 12 , wherein the aluminum buffer cladding is between 200 nm thick and 40 microns thick. 
     
     
         14 . The combination defined in  claim 1 , wherein the fine wire conductor includes a plurality of said glass/silica fiber cores each with metallic buffer cladding, combined together in the fine wire conductor. 
     
     
         15 . The combination defined in  claim 1 , wherein the buffered glass/silica fiber core is coated with a biocompatible polymer coating. 
     
     
         16 . The combination defined in  claim 1 , wherein the pulsing device delivers an electrical pulse of about 30 to 35 joules over a period of no more than about 25 msec. 
     
     
         17 . The combination defined in  claim 1 , wherein the high intensity energy electrical pulsing device is a defibrillator. 
     
     
         18 . The combination defined in  claim 17 , wherein the defibrillator delivers an electrical pulse of about 30 to 35 joules over a period of no more than about 25 msec. 
     
     
         19 . The combination defined in  claim 1 , including a plurality of said glass/silica fiber cores each with metallic buffer cladding, bundled together as multiple filars to act as a single conductor of the high electrical pulse. 
     
     
         20 . The combination defined in  claim 19 , wherein the high intensity energy electrical pulsing device is a defibrillator.